The paper shows the approach toward the calculation of one of the bigger PFRP （Pultruded Fiber Reinforced Polymer） structure realized in high seismic zone, i.e., a covering structure of an historic church stroked an...The paper shows the approach toward the calculation of one of the bigger PFRP （Pultruded Fiber Reinforced Polymer） structure realized in high seismic zone, i.e., a covering structure of an historic church stroked and partially collapsed by earthquake in L＇Aquila （Italy）, the 4 April 2009. The goal regards the analysis and evaluation of seismic performance of that structure made by very light and elastic-brittle material, as FRP material, in a moment in which there is a loss of technical recommendation for specific calculation in seismic field, indeed actually some deepening already present in literature allows only static field. The covering structure is an all FRP spatial-reticular with elements made by pultrusion process, connection plates by bag molding process and steel bolts. The PFRP structure covers more than 1000 meters squares surface with 32 meters height and only 100 kN weight. Detail performance of first part of PFRP structure through mode vibrations and involved percentage mass deduced by numerical approach with discussion of employment＇s perspectives of PFRP material in seismic zones than traditional material are showed.展开更多
It is a complicated dynamic phenomenon when a transient pressure pulse is triggered by two high-speed trains passing each other in a tunnel. The air pressure pulse is a transient excitation to side wall of the car bod...It is a complicated dynamic phenomenon when a transient pressure pulse is triggered by two high-speed trains passing each other in a tunnel. The air pressure pulse is a transient excitation to side wall of the car body. It can stimulate almost all vibration modes of the car body and the correlated assemblies, cause serious aerodynamic noise, and have important impacts on car body distortion, train noise, and operation safety. This article analyzes the time- frequency characteristics and main parameters of field-measured the air pressure wave, and its relationship with the train velocity as well as the vibration of the car body. Cepstrum analysis concludes that in the process of the meeting, the air pressure wave in tunnel crossing is a multiplying pressure wave instead of a superposed wave. The pressure pulse during the meeting is non-symmetrical one featured with a sharp front, large amplitude, fluctuating central sec- tion, and less sharp tail. The pulse width is inversely proportional to the train speed. As the speed increases, the impulse amplitude is amplified, and the speed of pulse front is advanced.展开更多
According to Kirchhoff-Love's assumptions, this paper establishes linear system of equations for solving eigen frequency constant and corresponding mode shape. Using engineer-ing and numerical analysis software Ma...According to Kirchhoff-Love's assumptions, this paper establishes linear system of equations for solving eigen frequency constant and corresponding mode shape. Using engineer-ing and numerical analysis software Matlab5.2 and method of coefficient determinant searching arithmetic, eigen frequency constant and mode shape of the stator with i.d./ o.d. ratio of 0.1, 0.3, 0.35, 0.6 and different vibration modes are accurately solved and analyzed. By means of Newton interpolation method, contributions of transverse deflection amplitude and vibration energy corresponding to various modes are determined. This paper offers a valid theoretical foundation for the optimum design of the stator of disk-shaped ultrasonic motors. Furthermore, according to results of numerical analysis, several choosing principles of vibration modes are summarized.展开更多
Using the axial symmetry results of marker and cell (MAC) method as initial value in this paper, two numerical calculating methods are presented for the late wavemaking response induced by explosion in harbour. One of...Using the axial symmetry results of marker and cell (MAC) method as initial value in this paper, two numerical calculating methods are presented for the late wavemaking response induced by explosion in harbour. One of the methods is the superposition method of the vibration mode based on fluid slosh in container. Another one is the joining method of the MAC results with the shallow wave theory calculation in time domain. As a practical example, it is conducted to the numerical calculation about 1000 ton TNT equivalent explosion within touch of water surface. The results show that it can be rationally described with the methods to the wavemaking progress and character. The numerical results are identical with the observed scene on the spot experiment. The methods are simple and applicable in the engineering design.展开更多
文摘The paper shows the approach toward the calculation of one of the bigger PFRP （Pultruded Fiber Reinforced Polymer） structure realized in high seismic zone, i.e., a covering structure of an historic church stroked and partially collapsed by earthquake in L＇Aquila （Italy）, the 4 April 2009. The goal regards the analysis and evaluation of seismic performance of that structure made by very light and elastic-brittle material, as FRP material, in a moment in which there is a loss of technical recommendation for specific calculation in seismic field, indeed actually some deepening already present in literature allows only static field. The covering structure is an all FRP spatial-reticular with elements made by pultrusion process, connection plates by bag molding process and steel bolts. The PFRP structure covers more than 1000 meters squares surface with 32 meters height and only 100 kN weight. Detail performance of first part of PFRP structure through mode vibrations and involved percentage mass deduced by numerical approach with discussion of employment＇s perspectives of PFRP material in seismic zones than traditional material are showed.
基金supported by the National Science and Technology Pillar Programs of China (No.2009BAG12A01-E02,No. 2009BAG12A01-E03 and No. 2009BAG12A01-E04)
文摘It is a complicated dynamic phenomenon when a transient pressure pulse is triggered by two high-speed trains passing each other in a tunnel. The air pressure pulse is a transient excitation to side wall of the car body. It can stimulate almost all vibration modes of the car body and the correlated assemblies, cause serious aerodynamic noise, and have important impacts on car body distortion, train noise, and operation safety. This article analyzes the time- frequency characteristics and main parameters of field-measured the air pressure wave, and its relationship with the train velocity as well as the vibration of the car body. Cepstrum analysis concludes that in the process of the meeting, the air pressure wave in tunnel crossing is a multiplying pressure wave instead of a superposed wave. The pressure pulse during the meeting is non-symmetrical one featured with a sharp front, large amplitude, fluctuating central sec- tion, and less sharp tail. The pulse width is inversely proportional to the train speed. As the speed increases, the impulse amplitude is amplified, and the speed of pulse front is advanced.
文摘According to Kirchhoff-Love's assumptions, this paper establishes linear system of equations for solving eigen frequency constant and corresponding mode shape. Using engineer-ing and numerical analysis software Matlab5.2 and method of coefficient determinant searching arithmetic, eigen frequency constant and mode shape of the stator with i.d./ o.d. ratio of 0.1, 0.3, 0.35, 0.6 and different vibration modes are accurately solved and analyzed. By means of Newton interpolation method, contributions of transverse deflection amplitude and vibration energy corresponding to various modes are determined. This paper offers a valid theoretical foundation for the optimum design of the stator of disk-shaped ultrasonic motors. Furthermore, according to results of numerical analysis, several choosing principles of vibration modes are summarized.
基金Subsidized subject financially supported by the National Natural Science Foundation of China
文摘Using the axial symmetry results of marker and cell (MAC) method as initial value in this paper, two numerical calculating methods are presented for the late wavemaking response induced by explosion in harbour. One of the methods is the superposition method of the vibration mode based on fluid slosh in container. Another one is the joining method of the MAC results with the shallow wave theory calculation in time domain. As a practical example, it is conducted to the numerical calculation about 1000 ton TNT equivalent explosion within touch of water surface. The results show that it can be rationally described with the methods to the wavemaking progress and character. The numerical results are identical with the observed scene on the spot experiment. The methods are simple and applicable in the engineering design.
